First, realize that not one, but at least 3 comprehensive meta analyses (see IQWiG, Institut für Qualität und Wirtschaftlichkeit im Gesundheitswesen; “Rapid-acting insulin analogues in diabetes mellitus type 1: Superio…”; 06 Jun 2007 for details of a fairly recent study done in Germany, another was done in Canada last year which found the same result) have proven that rapid-acting insulin analogs do NOT deliver superior glycemic control. Although many people swear otherwise, having tried every rapid-acting analog and I’m starting to believe that they’re a drug company scam. In my experience, they’re all basically no better than regular, although do differ on claims against long-acting analogs, but just realize that the motivation of the drug companies is to make money and keep us well enough to stay alive, but sick enough to require their product for life. Also, your own diabetes mileage may vary with every insulin, but the simple fact is that insulin analogs are not insulin, and there has never been any long-term trials of these products, the people now using them are the long-term trials!
I would also refer you to a useful article regarding insulin dosages published in Diabetes Health magazine about how smaller dosages work much more rapidly than larger doses, so your dosage size may influence how quickly it goes to work and how long your dose lasts. Also, realize that U-40 insulin (no longer sold in the U.S. except for animals such as dogs and cats) also work much more rapidly than more concentrated U-100 insulin.
Having said all of this, my own experience with each of the rapid-acting analogs was as follows:
Humalog: Worked fastest, but also had the shortest duration of activity
Novolog: Did not reduce my blood glucose for at least 3 hours (so much for the 15 minute claim) and easily lasted about 8 hours, making it more expensive regular insulin in my own experience.
Apidra: Fell somewhere in between Humalog and Novolog both in terms of speed of action and duration of activity.
Just remember, these are MY experiences, and your own personal experience will very likely differ. No two people experience things the same way, so as they say “YMMV” (your mileage may vary).